Combined reed and relay device



Sept. 12, 1944. H. w. APPEL 2,357,925

COMBINED REED AND RELAY DEVICE Filed Aug. '7, 1942 Tlcl.

J 7 i /FCU/T f4 P:4f /Z 4Z l l INVENTOR Haw/PY W 4ans/ ATTORNEYlPatented Sept. l2, 1944 COMBINED REED AND RELAY DEVICE Henry W. Appel,Kew Garden Hills, N. Y., assignor to Radio Corporation of America, acorporation oi' Delaware Application August 7, 1942, Serial No. 453,933

1 Claim.

My present invention relates to tuned reed devices, and moreparticularly to a tuned reed device which concurrently functions as arelay.

In application Serial No. 403,736, filed July 23, 1941, by H. B. Deal,and in my copending ap-l plication Serial No. 432,549, filed February25, 1942, there are shown radio alarm systems of the so-called alerttype. In these systems selective reeds, tuned to predetermined controltones, function to close respective electromagnetic relay circuits.These relay circuits are energized from the receiver power circuit, andutilize special contact elements and switches.

It is one of the main objects of my present invention to conserve relaycontacts and power in a receiver of the "alert type, by providingaselective reed vdevice which is constructed simultaneously to functionas a vrelay for closing an alarm circuit.

Another important object of my invention is tol provide a selectivereed, tuned to a control frequency, which functions as a relay device,and thereby is applicable to radio alarm receivers of the compact typewhere space requirements prevent the inclusion of an auxiliary relay.

Another important object of my invention is to provide a mechanicalresonator which concurrently functions to close a work circuit throughthe vibratory element of the resonator thereby eliminating the usualrelay circuit which is energized by the actuation of the vibratoryelement.

Another object of my invention is to provide a frequency-responsive reedwhich closes an electromagnet circuit upon actuation of the reed;closing of the circuit simultaneously closing a work circuit through thereed per se.

Still other objects of my invention are to improve generally thesimplicity and efficiency of reed-responsive circuits, andmoreespecially to Fig. 2 shows the rear view of a modified form of relaydevice,

Fig. 3 shows an end view, partly sectioned, of the modification of Fig.2.

Referring, now, to the drawing, I have shown an electromagnet devicecomprising a magnetic yoke l whose central core 2 has wound about it acoil 3. There is providedlan armature 4 made of resilient magneticmaterial. The armature 4 may be a strip of spring steel whose lower endis soldered, or welded, to the lower lip I of yoke I. Armature 4 isactuated by core 2 as current flows through coil 3. It is to be clearlyunderstood that the electromagnet 4-2-3 may be construct in any wellknown manner, other than schematically represented herein. The armature4 and yoke I are shown in section; the shapes of these elements areunimportant. Oi course, the armature should be of such construction thatthe armature can be periodically displaced about a mean position as thecontrol current flows through coil 3. The yoke l will be insulated fromthe chassis on which it rests.

The current flowing through coil 3 may be of a predetermined frequency,say 24 cycles. It may be derived from the detector of a radio receiver.

' The latter mayreceive modulated carrier waves provide a combined reedand relay device which,A

which include the 24 cycle note as a modulation component. As explainedin the aforesaid Deal application (or in my aforementioned application),one frequency on the carrier represents an on signal so far as thereceiver alarm circuit is lconcerned. A diferent frequency, for example30 cycles, corresponds to off signal. In actuating the alarm Circuit thetransmitter applies the on control frequency to the carrier. At thereceiver the process of demodulation provides the control frequency atthe detector output terminals. Y

The control frequency current may be amplified. It is thenapplied tocoil 3 for energizing the electromagnet and vibrating the armature 4.The armature has secured to it a highly selective reed 5. The reed hasits lower end secured to the armature as shown at 6. Of course, thelower end of reed 5 may be soldered to armature 4. The free end of reed5 is weighted, as at 1, so as to provide sharp mechanical resonance to24 cycles. In other words, and as well known to those skilled in the artof constructing reeds, the reed 5 will move with the armature 4 as aunit should the latter be actuated by currents other than 24 cycles.However, when the current flowing through coil 3 has the exact frequencyof 24 cycles, the resonant frequency of reed 5, the

reed will vibrate with a high degree of amplitude relative to its lowerpivot point. The inner face of the reed carries a contact point 8. Thelatter is arranged in alignment with the end of core 9.

A coil I is wrapped around core 9. One end of coil I0 is connected tothe positive terminal of a direct current source II, such as a smallbattery, of relatively low power but sumcient to magnetize core 9 andhold reed 5 against; it. Resistor I0' is arranged in series with coil I0to prevent complete shorting of source I I when coil I0 is snorted. Thenegative terminal of source II returns to the opposite end of coil IIJover a path comprising core 9, contact 8, reed 5, armature 4, yoke I andlead I2. It will now be seen that actuation of the reed at its resonantfrequency causes the contact 8 to touch the core 9. Normally, and in theabsence of 24 cycle current, any motion of armature 4 causing motion ofreed 5 will not be of sufficient angular amplitude to permit contactbetween point 8 and the core 9.

However, when the 24 cycle on" modulation tone is applied to the carrierfor setting off the remote receiver alarms, the receiver detector willprovide the 24 cycle control current to coil 3. Reed 5 will vibrate in awide arc and cause electrical contact between point 8 and core 9. Thisvwill close the electrical circuit through coil II! and cause source IIto energize the latter. As a result the core 9 will freeze the reed 5 inposition magnetically. Any desired form of work circuit, such as analarm circuit, may be completed through reed 5. Thus, one line I3 of thealarm circuit, which may contain a suitable current source such as thebattery II', is shown connected to the right end of core 9, and theopposite line i4 is shown connected to the xed -end of reed 5, the alarmcircuit being completed as follows: one side of source II', line I3,core 9, closed contact 8, reed 5, line I4l through the alarm device (notshown) and back to the other side of the source.

It will now be seen that when the contact point 8 is magneticallyretained against core 9, the alarm circuit will be closed through thepath traced above. The alarm circuit may include a visual currentindicator, such as a lamp,'or it may include an audible device, such asa buzzer, bell or siren. Further, the alarm circuit may include anyofthe devices referred to in my aforesaid application or in said Dealcase. The specific nature of the circuit closed through reed 5 and core9 is not material to the present invention.

When the off signal is applied to the carrier, the signal being a 30cycle tone, the detector at a receiver provides 30 cycle current. Thiscurrent is caused to iiow through the coil I4 of an electromagnet relaycore I5. A second reed I8 is arranged so as to vibrate in response tothe iiow of 30 cycle current through coil I4. The reed I6 is sharplyresonant to 30 cycles; the reed I8 is schematically represented sincethose skilled in the art are fully aware of the manner of constructingsharply tuned reed devices. The free Fig. 1.

end of reed I6 carries contact point Il which is arranged to contactfixed point I8. Of course, the reed I 6 vibrates in a wide arcsuiilcient to permit electrical contact between I7 and It solely inresponse to ow of 30 cycle current through coil I4.

Point I8 is connected by lead I9 to the positive side of the source IIthrough resistor i0. The negative terminal of source ll is connected bylead 20 to the ground. Hence, closure of reed switch l-IB results vinshort-circuiting of the source I I. The coil I0 is, therefore,de-energized, and core 9 will release the free end of reed 5. As aresult the alarm circuit through reed 5 will be opened. Of course, anyother arrangement can be employed to short, or partially short, coil I0upon actuation of the "01f reed I6. If desired, actuation of reed I6could energize a coil Whoseux is opposite to the iiux of coil Il). Whenthe ux is neutralized, the reed 5 will be released. Additionally, thefreeing of the on reed by mechanical means, such as tapping, isfeasible.

The electromagnet I-IE may be dispensed with, and the 30 cycle controlmodulation may be applied to coil 3. Further, the reed I5 may be securedat its lower end to the spring steel armature f3, as shown in Figs. 2and 3. In Fig. 2 reeds 5 and I6 are shown spaced. An insulation spacerI'I (Fig. 3) may secure the lower end of reed I6 to the armature 4. Thecore 2, in this modiiication, vibrates armature ll. If the current owthrough coil 3 is of 24 cycles, then reed E will vibrate and close thecircuit described in If the current owing through coil 3 is of 30cycles, then reed i6 vibrates to close its shorting circuit. Thenumerals shown in Figs. 2 and 3 correspond to those of Fig. 1.

While I have indicated and described several systems for carrying myinvention into effect, it will be apparent to one skilled in the artthat my invention is by no means limited to the particular organizationsshown and described, but that many modications may be made withoutdeparting from the scope of my invention, as set forth in the appendedclaim.

What I claim is:

In combination a rst reed tuned to a first control frequency, anelectromagnet energized by currents of said control frequency forvibrating said reed, means operated by the reed when its amplitude ofvibration reaches a predetermined amplitude for closing an alarmcircuit, a second electromagnet positioned with respect to the reed tomaintain the reed in its alarm circuitclosing position when said secondelectromagnet is energized, a circuit for said second electromagnetclosed by said reed when its amplitude of vibration reaches saidpredetermined amplitude, a second reed tuned to a second frequencydiderent from said first frequency, means energized by currents of saidsecond frequency for vibrating said second reed, and means operated bythe second reed for deenergizing said second electromagnet and therebyrelease the first reed.

HENRY W. APPEL;

